Acute Facial Paralysis
Sarah Mowry, M.D.
March 13, 2012
Disclosures
• None
Lecture Objectives
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Review facial nerve anatomy
Identify and classify facial nerve dysfunction
List causes of acute facial paralysis
Describe presumed etiology of Bell palsy
Explain the current treatment
recommendations for Bell palsy
Facial Nerve Anatomy
Right Ear
Left Ear
Facial Nerve Anatomy
Patient Work Up
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History
Physical
Audiogram
Electrodiagnostic testing
Imaging
Facial Nerve Exam
• Elicit history/exam findings of intratemporal branches
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Dry eye (Schirmer’s test)
Hyperacusis from stapedius dysfunction (reflex testing)
Dysguesia
Decreased sensation in the EAC (Hitselberger’s sign)
• Examine all branches of the nerve in the periphery
– Degree of weakness
– Presence of synkinesis
– Presence of spacticity
• Examine other cranial nerves
• Examine the EAC, TM and periauricular area
Classify
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House-Brackmann Scale
Sunnybrook
Sydney
Fisch Detailed Evaluation of Facial Symmetry
Yanagihara
Sunnybrook
House Brackmann Scale
Grade
Description
Gross function
Resting
appearance
Dynamic appearance
1
Normal
Normal
Normal
Normal
2
Mild dysfunction
Slight weakness with effort,
may have mild synkinesis
Normal
Mild oral and forehead
asymmetry; complete
eye closure with
minimal effort
3
Moderate
dysfunction
Obvious asymmetry with
movement, noticeable
synkinesis or contracture
Normal
Mild oral asymmetry,
complete eye closure
with effort, slight
forehead movement
4
Moderately severe
dysfunction
Obvious asymmetry,
disfiguring asymmetry
Normal
Asymmetrical mouth,
incomplete eye closure,
no forehead movement
5
Severe dysfunction
Barely perceptible movement
Asymmetric
Slight oral/nasal
movement with effort,
incomplete eye closure
6
Total paralysis
None
Asymmetric
No movement
Imaging in Bell Palsy
• The literature is filled with case reports of
missed diagnoses
• Contradictory evidence in the literature about
the prognostic value of MRI
– Most studies performed on 1.5 T magnets and
were qualitative in nature
• Some advocate imaging all patients.
– Is this the best use of scarce resources?
– If so, what is the timing of imaging?
Imaging in Bell’s Palsy
• Absolute indications
– Any patient with symptoms suspicious for stroke
– Palsy that progresses after 3 weeks
– Palsy that does not start to improve by 3 months
– Recurrent facial palsy
– Any patient contemplating surgical intervention
Facial Nerve Testing
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Faradic/galvanic stimulation
NET
MST
ENoG
EMG
• Only used for patients with complete paralysis
Patterns of Injury
Seddon (1940s)
• Neuropraxia
• Axonontmesis
• Neurontmesis
Sunderland (1950s)
• 1st degree – conduction
block and demyelination
• 2nd degree – axonal loss
• 3rd degree – disruption of
the endoneurium
• 4th degree disruption of the
perineurium
• 5th degree – disruption of
the epineurium
Patterns of Injury
• Neuropraxia
– No wallerian degeneration
– Axon and supporting tissue remains intact
• Axonotmesis
– Loss of continuity of the axon
– Wallerian degeneration occurs
• Neurotmesis
– Injury involves endoneurium
– Wallerian degeneration occurs
Pattern and Prognosis
• Neuropraxia will recover fully
• Axonotmesis will recover without synkinesis
• Neurotmesis will develop synkinesis and may
not recover fully
Ideal Test
• Be able to distinguish Axontmesis from
Neurontmesis
– Distinguish 2nd from 3rd degree injury
• All available testing can only distinguish 1st
degree injury from higher levels of injury
• Must make inferences about higher degrees of
injury from specific testing patterns.
Faradic/Galvanic stimulation
– No longer used
– Direct current applied to the stylomastoid
foramen
– Assess with visual response
– Does not predict prognosis
Nerve Excitability Test (NET)
• Electrode over main trunk and then a ground
electrode elsewhere
• Current increased until visual response is elicited
from normal side
– Threshold testing
• Same done for diseased side
• Difference of 3.5mAmp between sides indicates
poor prognosis for full recovery
• Drawback is inter-test variability and subjective
nature of response
Maximal Stimulation Test (MST)
• Increase the current on the normal side until
“maximal facial twitch” is seen
• Same level of current is then applied to the
diseased side
• Difference between the 2 sides is then graded
as equal, lesser or no response.
• Drawback is painful exam, very observer
dependent
Electroneurography (ENoG)
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Electrodes over the main trunk and then distally
Measures the compound muscle action potential
Suprathreshold stimulus is applied to both sides
Magnitude of the response is compared between
sides
• Not useful until Wallerian degeneration has
occurred
Electromyography
• Introduced in the 1960s to replace faradic and
galvanic stimulation
• Needle electrodes are placed into the muscle
• Measures a compound muscle action potential
– Fibrillation potentials and polyphasic action potentials
• Requires 21 days to quantify the degree of
denervation
• Evoked and voluntary EMG
Voluntary EMG
• Used to identify a false positive ENoG
• Suggests early “deblocking” of the FN
• Presence of CMAP on voluntary EMG is a sign
of good prognosis
Acute Facial Paralysis
• Unilateral facial dysfunction is common
– 20-30 per 100,000 per year for Bell’s Palsy
• Bilateral facial dysfunction is not common
– Less then 2% of acute palsies are bilateral
– Typically associated with systemic diseases
– Usually other manifestations of systemic diseases
are present
Acute Facial Palsy
• All that palsies is not Bell’s!
• 70-85% of acute unilateral facial paralysis is
idiopathic thus can be termed “Bell palsy”
Limb C, Niparko JK. The acute facial palsies. In: Neurotology 2nd Edition. Jackler RK, Brackmann DE Eds. Pg 1231.
Bilateral Acute Paralysis
• Bell palsy
• DM
• Heerfordt’s
fever
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Skull fracture
Bulbar palsy
Prophyria
Leukemia
(uveoparotid fever)
Myotonic
• PAN
dystrophy
• GBS
• Meningitis
• Myesthenia
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Botulism
gravis
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Leprosy
Polio
Lyme disease
Syphilis
Isoniazid
Post vaccine
neuropathy
Bell Palsy
• Sir Charles Bell first to attribute facial paralysis
to dysfunction of the facial nerve in 1821
• Cause has been a source of intense debate
• From 1930s-1960s felt to be due to vascular
insufficiency to the distal portion of the nerve
• Other theories included autonomic
dysfunction, autoimmune injury and viral
infection
Viral Hypothesis
• Murakami et al. Ann Int Med 1996;124(1):27
• Performed transtemporal facial nerve
decompression on 14 patients with Bell’s, 9
pts with HZ oticus and 12 controls
• Looked for HSV, VZV and EBV in endoneurial
fluid and post auricular muscle (PCR)
• Also drew serological studies on all patients
Viral Hypothesis
• Murakami et al 1996
– Identified HSV-1 DNA in the endoneurial fluid and
post auricular muscle of 11 of 14 patients (78%)
– Identified VZV in 89% of the Ramsey Hunt patients
– No viral DNA was identified in the control patients
– No HSV-1 or HSV-2 DNA was found in the Ramsey
Hunt or control patients
– HSV-1 antibody was present at higher incidence than
controls
– Viral antibody titers were not different between the
groups
Viral Hypothesis
• Murakami et al 1996
– Still not definitive
– Need to identify replicated viral particles in the
affected nerve
Mouse Model
• Mouse model
– Induce a transient facial paralysis by inoculating
HSV-1 onto the auricle or tongue of KOS mice
(60%)
– Inflammatory lesion within the facial nerve similar
to that seen in human Bell’s palsy
• Mixed injury of the facial nerve with extensive
demyelination of the distal nerve
– Electrical testing is similar to that seen in humans
Idiopathic Facial Paralysis
AKA Bell Palsy
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20-40 people/100,000 population per year
7-12% have recurrent Bell Palsy
<2% have bilateral involvement
Most common between age 20-65 yrs of age
Those over 60 yo have worse prognosis for full
recovery (30%)
• Children have very high rates of full recovery
(>90%)
Natural History of Bell Palsy
• Peitersen 1982
– 1011 patients in Copenhagen, Denmark over 15 yr
period
– Examined at onset and then at 1 week intervals
for 1 month then bimonthly exams until complete
resolution or 1 yr
– At presentation, 31% had incomplete paralysis,
69% had complete paralysis (non-standardized
scale)
Natural History
• Peitersen 1982
– Approximately half of patients presented with
pain in addition to facial palsy
• 50% had coincident pain
• 25% had pain precede palsy
• 25% had pain after palsy manifested
– 83% had taste alteration
– 71% had hyperacusis
– 12% had lacrimal dysfunction
Natural History
• Peitersen 1982
– All patients recovered function to some degree
– 71% achieved normal facial muscle function
– 80% regained taste function
– 97% regained lacrimal function
– 86% regained stapedial muscle function
Natural History
• Peitersen 1982
– Risk factors for incomplete recovery
• Diabetes
• Pregnancy
• Return of function beginning >3weeks from onset of
paralysis
• Postauricular pain
Treatment
• Numerous recommended treatments over the
years
– Medications, surgery, diet, physical therapy,
acupuncture
• Viral etiology treated with antiinflammatory
and antiviral therapies
• Current treatment investigations involves
corticosteroids, antivirals and surgery
Medical Therapy
• N Engl J Med. 2007;357(16):1598-607
– Prednisolone (85%) better than placebo (63%)
– Acyclovir+steroid no improvement over prednisolone
alone
• Cochrane Database Syst Rev. 2010 Mar
17;(3):CD001942.
– >1500 pts in 8 randomized studies
– Corticosteroids significantly reduced residual
weakness and synkinesis when compared to placebo
• Otol Neurotol. 2011 Jan;32(1):141-6.
– Improved outcome if started within 48 hours
Steroids
• Currently no consensus treatment regimen for
Bell’s palsy
– Prednisone 1mg/kg (QD or divided TID) for 10
days followed by a rapid taper
– Other studied regimens are:
• Prednisolone 25 mg BID x 10 days (NEJM)
• Cortisone 200mg QD x3d, 100mg QD x3d, 50mg QD x2d
• Methylprednisolone 1mg/kg/day x 10 day with 3-4 day
taper
Antivirals
• Multiple RCT and meta-analyses have failed to
demonstrate improved function with antiviral
monotherapy or in combination with steroids
– Acyclovir 400mg 5x/day
– Valacyclovir 1g BID x3-10days
• Cochrane review of 7 studies and 1987
patients did not demonstrate benefit with the
addition of antivirals to steroid therapy
Antivirals
de Almeida, J. R. et al. JAMA 2009;302:985-993
Is Medical Therapy the Only Option?
• 10-15% of patients will have some facial nerve
sequelae despite maximal medical therapy
• How do we identify these patients?
• Is there anything that we can do to improve
their outcome?
Surgery for Bell’s Palsy
• Controversial
• First described distal FN decompression in
1932 by Ballance and Duel.
– Distal 1 cm of the mastoid segment
– Presumed etiology was vascular congestion at the
stylomastoid foramen
• Chorda tympani neurectomy
• Progressed more proximally along the nerve
until the mid 1960s
Surgery for Bell’s Palsy
• 1961 William House described the MCF
technique to approach the IAC and FN
• 1965 Crabtree and House described the MCF
for FN decompression in Bell’s palsy and
trauma
• 1972 Fisch and Esslen reported on 12 patients
undergoing total FN decompression for Bell’s
palsy
MCF approach for Bell’s
• Fisch and Esslen 1972
– 11 of 12 had involvement of the labyrinthine
segment and geniculate ganglion
– 8 of 12 had involvement of the meatal segment
– 5 of 12 had involvement of the tympanic segment
– 3 patients tested with intraoperative EEMG
demonstrated conduction block proximal to GG at
the meatal foramen
• Confirm by Gantz et al (‘82) 15/16 had block at meatal
foramen
Anatomic Findings
• Ge and Spector 1981
– Anatomic study of the meatal foramen
demonstrating passage way of 0.68mm at the
meatal foramen due to tight arachnoid band
ENoG
• Less than 90% degeneration
prognosis for HB 1-2 is excellent
(90-95%)
• Greater than 95% degeneration
within 21 days prognosis for HB 12 is only 40-50%.
• Those who progress to 90%
degeneration will continue to
worsen to the >95% degeneration
more than 90% of the time.
• 85% may be prognostic of poor
outcome
– Clin Otolaryngol. 2006
Apr;31(2):144-8.
– Otol Neurotol 2011; 32(6):10311036
ENoG
• Cannot distinguish
between axonontmesis
and neurontmesis
• Daily testing until day 14
of paralysis
• Rapid progression of
degeneration suggests
worse degree of injury
• Progression to >95%
degeneration after 3
weeks still have good
prognosis
Gantz et al 1999
• 37 patients over 15 yrs
• Inclusion criteria
– Complete facial paralysis
– ENoG >90% degeneration
– Absent voluntary EMG CMAP
– Presentation within 14 days
• Early in study presentation within 21 days
Gantz et al 1999
• 3 arms
– Medical controls (n=11)
• Steroids 80 mg prednisone x 7 days with taper from
days 8-14
– Surgical controls (n=7)
• Group of patients operated on early in the study
between 14-21 days from onset of paralysis
– Study group (n=19)
• Underwent subtemporal craniotomy with
decompression of the distal IAC, labyrinthine, GG and
tympanic segments
Gantz et al 1999
Gantz et al 1999
• Steroids only vs intervention group p=0.0003
• Steroids vs surgical controls – not significantly
different
• <14 days vs >14 days at time of surgery was
significantly different p=0.001
• Patients who meet the inclusion criteria and
undergo surgery have a 91% chance of a good
outcome at 7 mo
MCF decompression
Right Ear
Left Ear
MCF decompression
Right ear
Left ear
MCF decompression
Indications for MCF decompression
• Complete facial nerve paralysis (HB 6/6)
• Electroneuronography
– >90% difference between the affected side and
the normal side
• Voluntary electromyography
– Absence of voluntary CMAP
• Presentation within 14 days of onset of
complete paralysis
• Patient desires operative intervention
Conclusions
• Differential diagnosis for acute unilateral facial
paralysis includes more than just Bell Palsy
• Majority of patients with Bell palsy do well
with “masterly inactivity”
• Corticosteroids DO significantly improve facial
nerve outcomes (HB 1 or 2) over placebo
• Maybe the jury is still out on antivirals
• Surgery significantly benefits a small group of
patients with severe Bell palsy
Thank you!